Just to illustrate that anything is possible
I live in a first floor flat (no garden or outside space) in the middle of a terraced street.
I have spurred off the mains water supply where it enters my flat and installed a 4040 high up on the wall of my hallway.
From there the waste and pure go under the floorboards, waste out through back wall and into drain pipe, pure re emerges in my living room and goes out of a bay window frame to a 15 m reel of hose secured on to a deep window ledge.
I unreel and lower the hose to my street parked van , loop it around the roof rack before feeding it into the van via a hoselock under the bumper
( that way its above head height and no trip hazard).
Vans tank has an over flow in much the same way a toilet cistern does so no chance of flooding the van. When I look out window and see water trickling from under the van I know the tank is full - simples, well, simple ish
there is always a way
